Question

Suppose the elements x and y combine to form two compounds xy2 and x3y2. When 0.1 mole of xy2 weighs 10 g and 0.05 mole of x3y2 weighs 9 g; the atomic weights of x and y are --->

Answer 1

let atomic weight of x = Mx
atomic weight of y = My

we know,
mole = weight /atomic weight
a/c to question,

mole of xy2 = 0.1
so,
0.1 = 10g/( Mx +2My)

Mx + 2My = 100g -------(1)

for x3y2 ; mole of x3y2 = 0.05

0.05 = 9/( 3Mx + 2My )

3Mx + 2My = 9/0.05 = 9× 20 = 180 g ---(2)
solve eqns (1) and (2)

2Mx = 80
Mx = 40g/mol

and My = 30g/mole

Answer 2

let atomic weight of x = Mx

atomic weight of y = My

we know,

mole = weight /atomic weight

a/c to question,

mole of xy2 = 0.1

so,

0.1 = 10g/( Mx +2My)

Mx + 2My = 100g -------(1)

for x3y2 ; mole of x3y2 = 0.05

0.05 = 9/( 3Mx + 2My )

3Mx + 2My = 9/0.05 = 9× 20 = 180 g ---(2)

solve eqns (1) and (2)

2Mx = 80

Mx = 40g/mol

and My = 30g/mole